The following new Cisco IOS Software features are available as a free software upgrade to current users of Cisco Catalyst 3750, Catalyst 3560, Catalyst 3550, and Catalyst 2970 series switches:

• Dynamic ARP inspection (DAI) and IP Source Guard (IPSG) support added to the IP Base image for the Cisco Catalyst 3750, Catalyst 3560, and Catalyst 3550 series. DAI and IPSG use a higher level of network security by preventing breaches such as "man-in-the-middle" attacks.

• Private VLAN support added to the IP Base image for the Cisco Catalyst 3750 and Catalyst 3560.

• Port security for voice VLANs support facilitates the configuration of voice VLANs for access ports such that an IP phone can not be moved within a switch unless the switch is reconfigured. Only one identified, secure PC is allowed per IP phone, and the PC can bypass the IP phone if desired.

Because of export restrictions on strong cryptography software, a separate image is required for the cryptographic features (Secure Shell [SSH] Protocol, Simple Network Management Protocol Version 3 [SNMPv3], and Kerberos Protocol). These software images can be downloaded from the corresponding Triple Data Encryption Standard (3DES) area of the links provided in this section. Note that the Cisco Advanced IP Services license is available only in cryptographic format.